I'm trying to replace the transmission filter on a 2003 E320 ; does anyone know where the transmission filter is on the engine? Thanks
I ' m trying to replace the transmission filter .

yeah take it to the dealer and spend your whole income, benz are pricey =D it cost 300 for a new KEY!

The filter is in the pan, you need to buy a service dipstick, which can not be left in place, and the cap on the filler tube needs to be broken and replaced.
The trans is a somewhat lifetime fill, (50,000 or so is suggested by most) and you must use MB fluid. The pan bolts are torqued or you will warp the pan, the converter can not be drained. I paid $250 at the dealer for a complete drain, filer, gasket etc. If you are not familiar with the filter, or have never done a trans, spend the money and or, find a good shop
And "Smart-Keys" are less than 200 US